The present invention relates to floor panels, and more particularly floor panels including a metallic pan and a cementitious material cast thereon.
A wide variety of access floor systems have been developed to provide a functional floor elevated above the structural floor of a building. Such systems were initially developed to provide a means of easily installing and subsequently accessing the large quantities of power and communications cable required in computer installations. These systems are now used in a host of environments enabling heating, cooling, and ventilating equipment; communications equipment and cables; and electrical distribution systems to be conveniently and accessibly located beneath the access floor.
Generally, an access floor system includes a plurality of floor panels supported on pedestals resting on the structural floor. In the most popular floors, each panel is two feet square and supported at each of its four corners on a pedestal which also supports one corner of the three adjacent panels. Optionally, grid channels or stringers are installed between the pedestals to provide lateral stability and increased strength to the system. In highly elevated systems (e.g., greater than 18 inches) additional lateral bracing is included and coupled to one or both of the pedestals and grid channels.
The floor panels used in such systems have a variety of constructions. One such panel comprises a planar high-density composite core and galvanized steel sheets laminated to the opposite core surfaces. Perimeter channels are welded to the steel cover sheets to provide an extremely serviceable panel. However, this panel utilizes combustible materials and has a relatively high cost-to-strength ratio.
Other types of panels used in other than access flooring environments include a planar cementitious core and metal cover sheets secured to one or both sides thereof. Examples of such constructions are illustrated in U.S. Pat. Nos. 3,759,009, entitled COMPOSITE LOAD BEARING PANELS, issued Sept. 18, 1973, to Ransome; 2,154,036 entitled CONSTRUCTIONAL FINISH DETAIL ELEMENT, issued Apr. 11, 1939, to Doherty; and 1,845,711, entitled TILE AND FLOOR WITH SPECIAL METAL WEARING SURFACE, issued Feb. 16, 1932, to Honig. However, these panels are also not without their drawbacks. Perhaps most significantly, known constructions for interconnecting the metal covers and cementitious cores are unsatisfactory, and more particularly are relatively expensive and/or structurally weak and unsuitable for access flooring.
In the Doherty device, a metal lath is welded to the metal pan prior to the casting of the cementitious material such that the lath secures the pan to the core in the completed article. However, this construction appears to be relatively labor intensive, and consequently relatively expensive. The Ransome and Honig devices include a plurality of tabs lanced from the planar sheet to be encapsulated tabs are oriented in a generally common direction over the entire tabs Honig are formed in a variety of directions all perpendicular to the edges of the square sheet. The cementitious material shifts or slides against the metal cover when loads are placed on the panels, which movement exerts horizontal shear forces on the tabs extending into the core material. More specifically, the cementitious core exerts an outwardly directed shear force from the center of the panel when a load is placed directly on the panel. Therefore, a portion of the tabs formed by lancing the pan generally away from the center of the panel are ripped or torn from the metal pan under this horizontal shear force. Such movement greatly detracts from the strength and integrity of the panel, leading to cracking of the cementitious core, excessive flexing of the panel, or even collapse.